Conventional communication systems on passenger vehicles (e.g., busses, vans, trains, aircraft, etc.) typically include a public address or passenger announcement (hereinafter PA) system for broadcasting communications such as announcements over one or more speakers installed in the vehicle cabin, and a separate cabin interphone system for the intra-cabin phone system, which the vehicle crewmembers (e.g., pilot/driver, cabin crew/flight attendants, etc.) use to communicate with each other. As shown in FIG. 1, the PA system 100 typically includes a central PA manager 120, a PA network 140 and a PA speaker 160 (although only one speaker 160 is shown, the PA system 100 may include additional speakers). The PA manager 120 handles the routing, distribution and prioritization of PA announcements so that announcements are broadcast via the PA network 140 and the PA speaker 160. Also as shown in FIG. 1, the interphone system 200 typically includes a central cabin interphone manager 220, an interphone network 240 and interphone handsets or stations 260 (although three stations, namely cockpit station 262, station 1 264 and station 7 266, are shown, the interphone system 200 may include fewer or additional stations). The interphone manager 220 performs a private automatic branch exchange (PABX) function so that vehicle crewmembers may communicate with each other by establishing cabin interphone calls via the interphone network 240 and stations 260. Since all of the audio routing, mixing, and distribution is performed by these centralized managers 120, 220, if one or both of the managers 120, 220 were to fail, the respective PA and interphone systems 100, 200 would cease functioning. Accordingly, duplicate managers 120, 220 as well as other redundant hardware must be provided in the vehicle to assure an acceptable level of overall system reliability.
The cabin interphone handsets 260 are typically located in various crew work areas or crew seating areas (including crew rests if applicable). These handsets 260 are connected through the cabin interphone network 240 (e.g., a wired network of twisted pair cables or the like) to a cabin interphone manager 220 that serves a function similar to a PABX or call-processing switch for a terrestrial telephone system.
As shown in FIG. 2, when a call is to be placed from one handset to another handset in the conventional system, a dial code is entered into the originating handset (e.g., “station 7” 266 as shown) and routed to the cabin interphone manager 220. The cabin interphone manager 220 receives the call setup request from the originating handset and performs call setup operations similar to what is performed by a switch of a plain old telephone system (POTS) by providing signals to the destination handset (e.g., “station 1” 264 as shown) to cause the destination handset to “ring.” Once the destination handset is picked up, the cabin interphone manager 220 switches or bridges the two handsets together and routes the audio signal from the originating handset to the destination handset and vice versa. This is essentially the same call setup/processing function that a terrestrial PABX performs to facilitate audio communication between two telephones. Every sample of audio is passed through and handled by the cabin interphone manager 220 and a failure of the cabin interphone manager 220 results in a total failure of the interphone system 200.
A PA system 100 typically accepts audio inputs from the handsets 260 (e.g., cockpit station 262) of the cabin interphone system 200 to create the audio for passenger announcements. Also, as shown in FIG. 3, the PA system 100 may accept audio from an entertainment system 300 (e.g., an audio/video system such as an in-flight entertainment system) so that in-vehicle video such as movies, etc. provided for passenger entertainment or information includes broadcast audio via the PA network 140 and speaker 160. The PA system 100 may also provide an audio feed and annunciation indication to any entertainment system 300 to cause entertainment pause and/or audio override. In conventional systems, entertainment pause and/or audio override is handled by the centralized PA manager 120. When an announcement for broadcast over the speaker 160 originates from a cabin interphone handset 260, the audio from the PA “call” is rerouted from the cabin interphone manager 220 to the PA manager 120 for distribution to overhead speakers 160.
That is, in the conventional system shown in FIG. 3, when a passenger announcement is to be initiated from a cabin interphone handset 260, a dial code for the PA system 100 is entered into the originating handset (e.g., “station 1” 264 as shown), the cabin interphone manager 220 informs the PA manager 120 of the request, and connects the audio signal from the originating handset to the PA manager 120. The PA manager 120 then distributes the audio received from the cabin interphone manager 220 to the appropriate overhead speaker or speakers. A “Push-to Talk” (PTT) button may be used on the handset 260 to trigger the announcement on and off.
In the conventional system as described and shown in FIGS. 1-3, the foregoing interphone and PA approaches cause the audio signal to pass through and be processed or routed by a number of different pieces of equipment. This has forced vehicles to have redundant hardware (e.g., a PA network consisting of first wiring and an interphone network consisting of second wiring), thereby increasing the vehicle weight and decreasing the vehicle's usable interior space.